This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We will perform simulations of small ion channels, antiamoebin and trichotoxin, in a water/membrane system, which consists of approximately 70,000 atoms. Microsecond time scale is required to estimate the conductance by counting ions crossing these channels in applied field. The calculated conductances will be compared with those measured electrophysiologically and with predictions of the diffusion-in-the-potential-of-mean-force model. Linking simulations with electrophysiology provides a strong, highly relevant test for the correctness of simulation results. If successful, this approach might motivate the development of improved hardware and software that would enable applying a similar strategy to more complex channels at longer times.